hyper threading.

[Anthony Atkielski]

em1897 at aol.com writes:

> When you get your machine running without a kernel
> let me know. The kernel is the key to the O/S. If you
> don't need networking and don't have many interrupts,
> then it probably doesnt matter that much.

The kernel represents only a small part of total system utilization and
throughput.  Even if everything is single-threaded through the kernel,
you can still get performance benefits from multiple processors, because
they can run userland processes in parallel.

If total system load is 5% kernel and 80% userland in a UP environment,
and moving to a MP environment doubles kernel overhead, total system
load has still increased by only 5%.

In general, many things must be single-threaded through the kernel
because of the need for proper synchronization.  Thus, the kernel always
shows more negative effects from MP than the system as a whole, but
since it is so small in the overall picture, MP still improves global
performance.

-- 
Anthony